The invention relates to a phosphorescent metal complex compound, a method for preparing same and a radiation emitting component, in particular an organic light emitting electrochemical cell (OLEEC).
Organic electroluminescent elements generally have at least one organic layer which is sandwiched between two electrodes. As soon as voltage is applied to the electrodes, electrons are injected from the cathode into the lowest unoccupied molecular orbitals of the organic light emitting layer and migrate to the anode. Correspondingly, holes are injected from the anode into the highest occupied molecular orbitals of the organic layer and migrate accordingly to the cathode. In the cases where migrating hole and migrating electron come together within the organic light emitting layer on a light emitting material, an exciton is produced which decays with the emission of light. In order that light can exit the electroluminescent element at all, at least one electrode must be transparent, in most cases said one electrode being of indium tin oxide which is used as the anode. The ITO layer is normally deposited on a glass substrate.
In the organic light emitting diodes (OLEDs), particularly in the case of the OLEDs based on small molecules, a so-called multilayer structure is implemented, because, in addition to the light emitting layer, efficiency-increasing layers such as hole and/or electron injection layers are disposed between the electrodes for better transference of the charge carriers. Highly reactive materials are often used here, which means that, among other things, encapsulation is critical for the service life of the light emitting element, as it protects the auxiliary layers from decomposition.
Alternatively, there are the so-called organic light emitting electrochemical cells (OLEECs) which are of simpler design than the OLEDs and which in most cases can be implemented by simply mounting an organic layer between two electrodes and subsequent encapsulation. The active layer of an OLEEC is generally made of a material which is a mixture of an ion conductor/electrolyte or also of a completely inert matrix (isolator) with an emitting species. Suitable for this purpose are ionic transition metal complexes (iTMC for short) such as ruthenium trisbipyridine hexafluorophosphates in polymer matrices. However, there is as yet an inadequate selection of suitable materials, there being in particular a dearth of blue emitting materials.